Sure thing! We've got 555 and we're gonna multiply it by 99. That's the same as adding 555 to itself 99 times.
Step 1: 0 + 555 = 555
Step 2: 555 + 555 = 1110
Step 3: 1110 + 555 = 1665
Step 4: 1665 + 555 = 2220
Step 5: 2220 + 555 = 2775
Step 6: 2775 + 555 = 3330
Step 7: 3330 + 555 = 3885
Step 8: 3885 + 555 = 4440
Step 9: 4440 + 555 = 4995
Step 10: 4995 + 555 = 5550
Step 11: 5550 + 555 = 6105
Step 12: 6105 + 555 = 6660
Step 13: 6660 + 555 = 7215
Step 14: 7215 + 555 = 7770
Step 15: 7770 + 555 = 8325
Step 16: 8325 + 555 = 8880
Step 17: 8880 + 555 = 9435
Step 18: 9435 + 555 = 9990
Step 19: 9990 + 555 = 10545
Step 20: 10545 + 555 = 11100
Step 21: 11100 + 555 = 11655
Step 22: 11655 + 555 = 12210
Step 23: 12210 + 555 = 12765
Step 24: 12765 + 555 = 13320
Step 25: 13320 + 555 = 13875
Step 26: 13875 + 555 = 14430
Step 27: 14430 + 555 = 14985
Step 28: 14985 + 555 = 15540
Step 29: 15540 + 555 = 16095
Step 30: 16095 + 555 = 16650
Step 31: 16650 + 555 = 17205
Step 32: 17205 + 555 = 17760
Step 33: 17760 + 555 = 18315
Step 34: 18315 + 555 = 18870
Step 35: 18870 + 555 = 19425
Step 36: 19425 + 555 = 19980
Step 37: 19980 + 555 = 20535
Step 38: 20535 + 555 = 21090
Step 39: 21090 + 555 = 21645
Step 40: 21645 + 555 = 22200
Step 41: 22200 + 555 = 22755
Step 42: 22755 + 555 = 23310
Step 43: 23310 + 555 = 23865
Step 44: 23865 + 555 = 24420
Step 45: 24420 + 555 = 24975
Step 46: 24975 + 555 = 25530
Step 47: 25530 + 555 = 26085
Step 48: 26085 + 555 = 26640
Step 49: 26640 + 555 = 27195
Step 50: 27195 + 555 = 27750
Step 51: 27750 + 555 = 28305
Step 52: 28305 + 555 = 28860
Step 53: 28860 + 555 = 29415
Step 54: 29415 + 555 = 29970
Step 55: 29970 + 555 = 30525
Step 56: 30525 + 555 = 31080
Step 57: 31080 + 555 = 31635
Step 58: 31635 + 555 = 32190
Step 59: 32190 + 555 = 32745
Step 60: 32745 + 555 = 33300
Step 61: 33300 + 555 = 33855
Step 62: 33855 + 555 = 34410
Step 63: 34410 + 555 = 34965
Step 64: 34965 + 555 = 35520
Step 65: 35520 + 555 = 36075
Step 66: 36075 + 555 = 36630
Step 67: 36630 + 555 = 37185
Step 68: 37185 + 555 = 37740
Step 69: 37740 + 555 = 38295
Step 70: 38295 + 555 = 38850
Step 71: 38850 + 555 = 39405
Step 72: 39405 + 555 = 39960
Step 73: 39960 + 555 = 40515
Step 74: 40515 + 555 = 41070
Step 75: 41070 + 555 = 41625
Step 76: 41625 + 555 = 42180
Step 77: 42180 + 555 = 42735
Step 78: 42735 + 555 = 43290
Step 79: 43290 + 555 = 43845
Step 80: 43845 + 555 = 44400
Step 81: 44400 + 555 = 44955
Step 82: 44955 + 555 = 45510
Step 83: 45510 + 555 = 46065
Step 84: 46065 + 555 = 46620
Step 85: 46620 + 555 = 47175
Step 86: 47175 + 555 = 47730
Step 87: 47730 + 555 = 48285
Step 88: 48285 + 555 = 48840
Step 89: 48840 + 555 = 49395
Step 90: 49395 + 555 = 49950
Step 91: 49950 + 555 = 50505
Step 92: 50505 + 555 = 51060
Step 93: 51060 + 555 = 51615
Step 94: 51615 + 555 = 52170
Step 95: 52170 + 555 = 52725
Step 96: 52725 + 555 = 53280
Step 97: 53280 + 555 = 53835
Step 98: 53835 + 555 = 54390
Step 99: 54390 + 555 = 54945

So, 555*99 = 54945